1. Field of the Invention
The present invention relates to a drug administering apparatus having an excellent sustained release property for a drug or liposome in which a liposome preparation or composition encapsulating therein a drug to be administered to a biological organism is immobilized in a polymeric substance fixed on a surface of an insoluble support.
2. Description of the Prior Art
Liposomes mainly consisting of phospholipids and various lipids as membrane constituting components have excellent biocompatibility and can be safely used for oral drugs, or parenteral drugs such as an injection solution or an ointment. Application of liposomes to targeting therapy is being studied due to their tendency to concentrate in the reticuloendothelial system and ability to pass through cerebral blood vessels. However, conventional liposomes have poor physical and chemical stability and short life in biological organisms; their membranes are easily damaged in vitro or in vivo and thereupon spontaneously release the drug.
General drugs upon being administered are absorbed from an administered portion of a human body and spread to the entire body through the blood and lympha. The drugs reach a diseased portion of the body through complex procedures. The effect of the drug is closely related to the drug concentration in blood. As can be seen from FIG. 1 (typical change in drug concentration in blood), how to maintain an effective drug concentration for a given therapy time is an important problem in economically performing therapy without causing side effects.